Hey i dont really know much about cars and i dont claim to but the check engine light in my 1997 Volvo GLT Turbo keeps turning on and the error code is P0303 meaning a misfire in cylinder after a day or two it will turn off and then erraticly turn back on during daily use. The mechanic says it is a blown head gasket but we got a second opinion and they said it was not and they replaced all of the spark plugs and wires and they also checked the pressure in the cylinders and it was normal. This problem has me baffeled does anyone have any ideas?

 

Might also be a bad injector.